Soft tissues, such as ligaments, tendons and muscles, are attached to a large portion of the human skeleton. In particular, many ligaments and tendons are attached to the bones which form joints, such as shoulder and knee joints. A variety of injuries and conditions require attachment or reattachment of a soft tissue to bone. For example, when otherwise healthy tissue has been torn away from a bone, surgery is often required to reattach the tissue to the bone to allow healing and a natural reattachment to occur.
A number of devices and methods have been developed to attach soft tissue to bone. These include screws, staples, cement, suture anchors, and sutures alone. Some of the more successful methods involve the use of a suture anchor to attach a suture to the bone, and tying the suture in a manner that holds the tissue in close proximity to the bone.
The tissue may be attached to the bone during open surgery, or during closed (e.g., arthroscopic) surgical procedures. Closed surgical procedures are preferred since they are less invasive and are less likely to cause patient trauma. In a closed surgical procedure, the surgeon performs diagnostic and therapeutic procedures at the surgical site through small incisions, called portals, using instruments specially designed for this purpose. One problem encountered in the less invasive, closed surgical procedures is that the surgeon has significantly less room to perform the required manipulations at the surgical site. Thus, devices and methods are needed which will allow a surgeon to effectively and easily attach tissue to bone in the small spaces provided by less invasive surgical procedures.
Conventional methods for attaching soft tissue to bone typically require that the surgeon tie a knot in the suture thread to attach the suture to an anchor, or to attach the tissue to the bone using the suture. Knot tying at the surgical site in closed surgical procedures, and even in open surgery, is difficult and time consuming due to inherent space constraints. Further, knots and other bulky attachment means can irritate tissue over time.
Knotless suture anchor systems have been developed for use with closed surgical procedures, and U.S. Pat. No. 5,569,306 provides one example of such a system. Although generally useful, such systems can be limited to use only with certain types or shapes of tissue, or to use with certain anatomical structures. Proper attachment of soft tissue requires that it be placed in the anatomically correct position to promote optimal healing.
A further knotless suture anchor system is disclosed in U.S. Pat. No. 5,782,864. While useful, the suture anchor and system disclosed in this patent is not believed to be absorbable. That is, the suture anchor is made of a metal, which will remain permanently implanted in the patient.
Further, some conventional knotless suture anchor systems may require, in order to attach a broader array of tissue shapes to bone, that the suture anchor pass though the tissue to be attached. This is undesirable because it unnecessarily irritates the injured tissue and it requires opening a much larger hole in the tissue.
There is thus a need for an improved system for anchoring soft tissue to bone which reduces or eliminates the need to tie suture knots at the surgical site. Further, there is a need for an improved system for anchoring soft tissue to bone which is fast and easy to deploy. It would also be advantageous to provide at least a partially absorbable knotless suture anchor and system so as to encourage natural regrowth of the damaged or torn tissue.